Knowledge-Aided STAP Using Low Rank and Geometry Properties

This paper presents knowledge-aided space-time adaptive processing (KA-STAP) algorithms that exploit the low-rank dominant clutter and the array geometry properties (LRGP) for airborne radar applications. The core idea is to exploit the fact that the clutter subspace is only determined by the space-time steering vectors, {red}{where the Gram-Schmidt orthogonalization approach is employed to compute the clutter subspace. Specifically, for a side-looking uniformly spaced linear array, the} algorithm firstly selects a group of linearly independent space-time steering vectors using LRGP that can represent the clutter subspace. By performing the Gram-Schmidt orthogonalization procedure, the orthogonal bases of the clutter subspace are obtained, followed by two approaches to compute the STAP filter weights. To overcome the performance degradation caused by the non-ideal effects, a KA-STAP algorithm that combines the covariance matrix taper (CMT) is proposed. For practical applications, a reduced-dimension version of the proposed KA-STAP algorithm is also developed. The simulation results illustrate the effectiveness of our proposed algorithms, and show that the proposed algorithms converge rapidly and provide a SINR improvement over existing methods when using a very small number of snapshots.Comment: 16 figures, 12 pages. IEEE Transactions on Aerospace and Electronic Systems, 201

Advances in Polar Materials for Lithium-Sulfur Batteries

Lithium-sulfur batteries are regarded as promising candidates for energy storage devices due to their high theoretical energy density. Various approaches are proposed to break through the obstacles that are preventing Li-S batteries from realizing practical application. Recently, the importance of the strong chemical interaction between polar materials and polysulfides is recognized by researchers to improve the performance of Li-S batteries, especially with respect to the shuttle effect. Polar materials, unlike nonpolar materials, exhibit strong interactions with polysulfides without any modification or doping because of their intrinsic polarity, absorbing the polar polysulfides and thus suppressing the notorious shuttle effect. The recent advances on polar materials for Li-S batteries are reviewed here, especially the chemical polar-polar interaction effects toward immobilizing dissolved polysulfides, and the relationship between the intrinsic properties of the polar materials and the electrochemical performance of the Li-S batteries are discussed. Polar materials, including polar inorganics in the cathode and polar organics as binder for the Li-S batteries are respectively described. Finally, future directions and prospects for the polar materials used in Li-S batteries are also proposed